.TH LJ4_FONT @MAN5EXT@ "@MDATE@" "groff @VERSION@"
.SH NAME
lj4_font \- groff fonts for use with devlj4
.
.
.\" ====================================================================
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.\" ====================================================================
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.\"
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.
.\" ====================================================================
.SH DESCRIPTION
.\" ====================================================================
.
Nominally,
all Hewlett-Packard LaserJet\~\%4-series and newer printers have the
same internal fonts:
45 scalable fonts and one bitmapped Lineprinter font.
.
The scalable fonts are available in sizes between 0.25 points and 999.75
points,
in 0.25-point increments;
the Lineprinter font is available only in 8.5-point size.
.
.
.LP
The LaserJet font files included with
.B groff
assume that all printers since the LaserJet\~4 are identical.
.
There are some differences between fonts in the earlier and more recent
printers,
however.
.
The LaserJet\~4 printer used Agfa Intellifont technology for 35 of the
internal scalable fonts;
the remaining 10 scalable fonts were TrueType.
.
Beginning with the LaserJet\~\%4000-series printers introduced in 1997,
all scalable internal fonts have been TrueType.
.
The number of printable glyphs differs slightly between Intellifont and
TrueType fonts
(generally,
the TrueType fonts include more glyphs),
and
there are some minor differences in glyph metrics.
.
Differences among printer models are described in the
.I "PCL\~5 Comparison Guide"
and the
.I "PCL\~5 Comparison Guide Addendum"
(for printers introduced since approximately 2001).
.
.
.LP
LaserJet printers reference a glyph by a combination of a 256-glyph
symbol set and an index within that symbol set.
.
Many glyphs appear in more than one symbol set;
all combinations of symbol set and index that reference the same glyph
are equivalent.
.
For each glyph,
.BR hpftodit (@MAN1EXT@)
searches a list of symbol sets,
and selects the first set that contains the glyph.
.
The printing code generated by
.B hpftodit
is an integer that encodes a numerical value for the symbol set in the
high byte(s),
and the index in the low byte.
.
See
.BR groff_font (@MAN5EXT@)
for a complete description of the font file format;
symbol sets are described in greater detail in the
.IR "PCL\~5 Printer Language Technical Reference Manual" .
.
.
.LP
Two of the scalable fonts,
Symbol and Wingdings,
are bound to 256-glyph symbol sets;
the remaining scalable fonts,
as well as the Lineprinter font,
support numerous symbol sets,
sufficient to enable printing of more than 600 glyphs.
.
.
.LP
The metrics generated by
.B hpftodit
assume that the DESC file contains values of 1200 for
.I res
and 6350 for
.IR unitwidth ,
or any combination
(e.g.,
2400 and 3175)
for which
.IR res \~\[tmu]\~ unitwidth \~=\~7\|620\|000.
.
Although HP PCL\~5 LaserJet printers support an internal resolution of
7200 units per inch,
they use a 16-bit signed integer for cursor positioning;
if
.B devlj4
is to support U.S.\& ledger paper (11\~in\~\[mu]\~17\~in;
in = inch),
the maximum usable resolution is 32\|767\~\[di]\~17,
or 1927 units per inch,
which rounds down to 1200 units per inch.
.
If the largest required paper size is less
(e.g.,
8.5\~in\~\[mu]\~11\~in,
or A5),
a greater
.I res
(and lesser
.IR unitwidth )
can be specified.
.
.
.\" ====================================================================
.SH LIMITATIONS
.\" ====================================================================
.
Font metrics for Intellifont fonts were provided by Tagged Font Metric
(TFM) files originally developed by Agfa/Compugraphic.
.
The TFM files provided for these fonts supported 600+ glyphs and
contained extensive lists of kerning pairs.
.
.
.LP
To accommodate developers who had become accustomed to TFM files,
HP also provided TFM files for the 10 TrueType fonts included in the
LaserJet\~4.
.
The TFM files for TrueType fonts generally included less information
than the Intellifont TFMs,
supporting fewer glyphs,
and in most cases,
providing no kerning information.
.
By the time the LaserJet\~4000 printer was introduced,
most developers had migrated to other means of obtaining font metrics,
and support for new TFM files was very limited.
.
The TFM files provided for the TrueType fonts in the LaserJet\~4000
support only the Latin 2 (ISO 8859-2) symbol set,
and include no kerning information;
consequently,
they are of little value for any but the most rudimentary documents.
.
.
.LP
Because the Intellifont TFM files contain considerably more information,
they generally are preferable to the TrueType TFM files even for use
with the TrueType fonts in the newer printers.
.
The metrics for the TrueType fonts are very close,
though not identical,
to those for the earlier Intellifont fonts of the same names.
.
Although most output using the Intellifont metrics with the newer
printers is quite acceptable,
a few glyphs may fail to print as expected.
.
The differences in glyph metrics may be particularly noticeable with
composite parentheses,
brackets,
and braces used by
.BR eqn (@MAN1EXT@) .
.
A script,
located in
.IR @FONTDIR@/\:devlj4/\:generate ,
can be used to adjust the metrics for these glyphs in the special font
\[lq]S\[rq] for use with printers that have all TrueType fonts.
.
.
.LP
At the time HP last supported TFM files,
only version 1.0 of the Unicode standard was available.
.
Consequently,
many glyphs lacking assigned code points were assigned by HP to the
Private Use Area (PUA).
.
Later versions of the Unicode standard included code points outside the
PUA for many of these glyphs.
.
The HP-supplied TrueType TFM files use the PUA assignments;
TFM files generated from more recent TrueType font files require the
later Unicode values to access the same glyphs.
.
Consequently,
two different mapping files may be required:
one for the HP-supplied TFM files,
and one for more recent TFM files.
.
.
.\" ====================================================================
.SH FILES
.\" ====================================================================
.
.TP
.I @FONTDIR@/\:devlj4/\:DESC
device description file
.
.
.TP
.IR @FONTDIR@/\:devlj4/\: F
font description file for font
.I F
.
.
.TP
.I @FONTDIR@/\:devlj4/\:generate
corrects Intellifont-based height metrics for several glyphs in the
special font for TrueType CG Times (LaserJet\~4000 and later).
.
.
.\" ====================================================================
.SH "SEE ALSO"
.\" ====================================================================
.
.BR groff (@MAN1EXT@),
.BR hpftodit (@MAN1EXT@),
.BR grolj4 (@MAN1EXT@),
.BR groff_font (@MAN5EXT@)
.
.
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